BootMed Live CD
The BootMed Live CD is an Ubuntu Remix for those new to Linux. It's main goal is to help the average Windows user to recover a computer that will not boot. Besides troubleshooting boot problems, there are many other things that BootMed can guide you through.
Clonezilla, based on DRBL, Partition Image, ntfsclone, and udpcast, allows you can massively clone many (40 plus!) computers simultaneously. Read more
The CD aims to be fast, small in size (~50mb), and use minimal resources to get that disk partitioned the way you want it. GParted LiveCD uses Xorg, the lightweight Fluxbox window manager, and the latest 2.6 Linux Kernel.
grml is a bootable CD (Live-CD) based on Knoppix and Debian. grml includes a collection of GNU/Linux software especially for users of texttools and system administrators. grml provides automatic hardware detection. You can use grml for example as a rescue system, for analyzing systems/networks or as a working environment.
Inquisitor is an open-source hardware testing and certification system, suitable for both enterprise and home use, customizable, modular and available in both serverless Live CD/DVD format and server-controlled network boot production system.
Mutagenix is a Slackware based distribution featuring automatic hardware detection using ArchLinux's lshwd, KDE 3.5, and GNOME 2.12.1.
Parted Magic is a ~30mb LiveCD/USB with it's only purpose being partitioning hard drives. Although GParted and Parted are the main programs, the CD/USB also offers programs like partimage, testdisk, fdisk, sfdisk, dd, ddrescue, etc...
Partimage Is Not Ghost
Partimage Is Not Ghost (PING) is a live Linux ISO based on LFS (Linux From Scratch). It can be burnt on a CD and booted, or integrated in a PXE/RIS environment. Several tools that make it the perfect choice for easily backing up and restoring whole partitions are included. It supports backups to and from SMB shares, backup of BIOS data, the ability to blank the local admin's password, creation of bootable restoration DVDs, the ability to partition and format a disk before installing Windows, and more. Read more
Recovery Kaboot is command line only and contains a number of recovery utilities. Its main purpose is to save you in the nick of time.
TheSSS (The Smallest Server Suite) is a lightweight server suite distributed as a live CD. It is designed for system administrators who need a small (less than 30MB) set of server software for small local area networks.